Properly wrap discarded statements (#10322)

Failing to do so lead the codegen to emit invalid code sometimes,
especially when C++ references were involved.

Fixes #10241

1 files changed, 19 insertions, 0 deletions

diff --git a/tests/cpp/t10241.nim b/tests/cpp/t10241.nim
new file mode 100644
index 000000000..21d6a0f4e
--- /dev/null
+++ b/tests/cpp/t10241.nim
@@ -0,0 +1,19 @@
+discard """
+  targets: "cpp"
+  action: "compile"
+"""
+
+type
+  String* {.importcpp: "std::string", header: "string".} = object
+
+proc initString*(): String
+    {.importcpp: "std::string()", header: "string".}
+
+proc append*(this: var String, str: String): var String
+    {.importcpp: "append", header: "string", discardable.}
+
+var
+  s1 = initString()
+  s2 = initString()
+
+s1.append s2